Vail ==== Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, collapsing , cross loaded, faceted, facets, high pressure, path, slab, slabs, sugar snow, sustrugi, weak layers, wind loaded, windloading, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 1/3/2008 7:02:03 AM Forecaster: Brad Sawtell Weather Synopsis Weather on the distant horizon looks like it could be dramatic, but for now let us just concentrate on the next 36 hours. Still mostly high thin clouds around the state and warm temperatures above the valley floors. Been hard to scour out that cold air. Winds have been fairly light out of the southwest as the high pressure ridge slowly moves eastward out of Colorado this afternoon. Models are showing a slow and steady increase in these winds tonight into Friday night. For very early Friday morning a weak impulse slaps us with a quick skiff of snow, favoring the San Juans and portions of the central mountains and possibly the Vail Pass and Steamboat zone. Maybe even up on Hoosier Pass. Not much to count, but favored areas may get an inch or two. Some timing issues arise by Friday night with the different models. One model is dumping some very impressive numbers on areas favored with southwest flow for Saturday, but can not quite buy into those yet. Fortunately I have till tomorrow morning to digest the incoming beta. Suffice it to say, by some point this weekend, things could get quite juicy. Bad news is that winds could get quite strong. More details in the Friday morning update. Weather Thursday Thursday Night Friday Temperature(°F) 28-33 15-20 31-36 Wind Speed(mph) 10-20 12-22 G 30s 15-25 G 40s Wind Direction SW SW WSW Sky Cover Increasing Mostly Cloudy Mostly Cloudy Snow(in) 0 0-1 Tr-2 Snowpack Discussion There have been many avalanches reported to the office since Tuesday with a few close calls. Thank you to those who have made reports! Most of the activity in the Vail Pass area has been slightly above treeling to just below treeline on south easterly aspects. Other activity around the zone has mostly occurred above treeline on north east through east and southerely aspects. Some of these avalanches have stepped down to deeper weak layers, resulting in 6 foot fracture lines. Three, yes three other very close calls occurred in the Loveland Pass area above treeline on an east, south east and a south south west aspects. A lone rider center punching a large size path was very lucky. Another group of two riders boarding on a loaded 40 degree slope. The report says that the snow "looked" stable. The third was another lone skier, who trigged a slide as they went from sustrugi to hard slab conditions. Areas of concern will continue to be steep wind loaded and cross loaded terrain facing north through east through south aspects at and above treeline. Many of the westerly aspects at and above treeline are either devoid of snow or now have very thin and weakening snow pack structure. Temperatures have been on the rise and will contiue today. Winds have for the most part been consitantly from the west but speeds have slowed. Yesterday on lower elevation slopes, the surface was actually becoming wet from the rapid warming. Reports of wet "roller balls" were common. Dense hard slab conditions will continue to be the problem as the slabs formed at the year's turn, formed above very weak faceted grains or sugar snow. Basal facets or sugar near the ground is also a problem, allowing avalanches to step down to deeper weak layers. Triggering larger sized avalanches is back in the picture. We will continue to also see smaller avalanches at and below treeline because the hard slabs are less present. Observers have reported finding weak scores when performing stability tests, usually failing below the hard slab and also just above the ground. Route finding will be the key to avoiding avalanches today. Avoid areas where hard slabs are below you. Be very mindful of where you get cracking. Hard slabs tend to not crack too much until you are near the edges of the slab, then they zipper open with lightning speed. Watch for obvious signs of instability including recent avalanching, cracking, collapsing and stronger over weaker layering. Avoid traveling on or below steep exposed slopes above treeline. Human triggered slides are probable above treeline on north through east to south aspects with recent windloading. Avalanche Danger The avalanche danger in the Vail Summit Zone is CONSIDERABLE above treeline on north, northeast, east, southeast, and south aspects. The danger is MODERATE on other aspects above treeline. Near treeline the danger is MODERATE on all aspects. Below treeline the danger is MODERATE on north, northeast, east, southeast, and south aspects, and LOW on other aspects.